1. Field of the Invention
The present invention relates generally to systems and methods for enterprise data management and more particularly, to multiplexing back-up data from several sources onto a single storage device.
2. Description of the Background Art
Networked client/server computer systems are becoming increasingly more common as the xe2x80x9cInformation Revolutionxe2x80x9d progresses. In a client/server computer network, the server computer is a computer that runs a set of services which are available to the client computers. The client computers are computers that run application programs through which the services are requested. The client computers and server computers are inter-coupled via a network. Such services may include database management, Network Information Services (NIS), and Network File System (NFS) programs. The services may operate within an environment that includes a back-up process. A back-up process copies data from an expensive disk storage media to a much less expensive tape storage media so as to provide a back-up copy of the data.
Typically when client computer data is backed-up by a server computer, the server computer backs-up client computer data to tapes in a serial manner, that is, one client computer at a time. This means that the server computer schedules a tape drive resource for backing-up a particular client computer""s data, and the tape drive is dedicated solely to that client computer until the client computer stops sending back-up data. In this manner, the back-up data are written to tape in a standardized format. One such standardized format is provided by the Tape ARchive(trademark) function of the UNIX(copyright) (a registered trademark of Novell, Inc. of Orem, Utah) operating system.
Dedicating such a resource to a single client computer during a back-up operation often does not fully utilize a tape drive""s data through-put capabilities and results in poor use of a critical resource. Therefore, what is needed is a system and method for keeping enough data available so that that a tape drive""s full through-put capabilities may be most completely realized.
The present invention is a system and method for multiplexed data back-up. Within the apparatus of the present invention, a back-up tape manager performs the actual multiplexed data back-up through use of multiple reading processes, a writing process, and a de-multiplexing process. The reading processes monitor the network for back-up data packets from individual client computers and inserts the data into a buffer within a shared memory area. The writing process multiplexes each client computer""s back-up data from the buffers in the shared memory with the back-up data from the other client computers onto a tape. The de-multiplexing process receives requests to retrieve data from a particular client computer that has been backed-up onto a tape and scans through the tape, copying only those sets of back-up data corresponding to that particular client computer. The de-multiplexing process reunites individual sets of back-up data from the tape into a single complete client computer data stream. An additional back-up scheduler unit enables the entire multiplexed data back-up process to be tailored to the performance capabilities of an individual set of client/server computer network resources.
Within the method of the present invention, a server computer receives back-up data over a network from a client computer. The server computer routes the back-up data to an empty buffer within a shared memory area where it attaches a client identification tag to the back-up data. The server computer then scans all of the buffers within the shared memory searching for any full buffers. If a full buffer is found, the server computer copies the client identification tag and the back-up data from the buffer onto a tape in the order in which the buffers fill up regardless of which client computer their data came from.
The back-up data is de-multiplexed in response to a user selecting a file to be retrieved from a back-up image corresponding to a client computer. A client identification tag corresponding to the file is then identified. In response, the server computer scans all the client identification tags from within a set of multiplexed data stored on a source tape. When a client identification tag is found to correspond to the identified client identification tag, the server computer transmits the data block associated with that client identification tag back to the requesting user. Alternatively, data can be de-multiplexed in response to a user command when making a duplicate copy of the source tape.
According to the apparatus and the method described, back-up data may be received from a plurality of client computers and multiplexed onto a single tape drive. In this manner not only may the tape drive resources be used to their fullest capacity, but also client computers need not wait for other client computers to complete their data back-up before they can begin their own.